There is a recognized need for timer valve assemblies that permit flow of water for certain periods of time. The current examples of such valves typically include a timer, a water inlet and an outlet. A water source, such as a spigot, is connected to the inlet while a hose or other watering device is coupled to the outlet. The valve assembly is controlled by a timing device which will open the valve and keep it open to allow water flow to the outlet. In such a manner, a user simply sets the timer for a pre-determined period of time. The user does not need to return to the valve assembly to shut off the water flow to prevent over-watering.
Various timer mechanisms have been used in the past. For example, an electronic timer has been used. Electronic timers may be analog or digital and may also use electrical power to actuate the on-off valve. Such timers are very accurate, but suffer from several shortcomings. If the electrical power is supplied by a battery, the timer has a limited life. Further, the timer must be constructed to protect the battery from outside elements, thereby increasing the weight of the device and the number of component parts. Alternatively, the electrical power may be supplied through a standard electrical outlet. However, this limits the effective range of the valve as it must be placed in proximity to an electrical outlet in order to function. Also, electrical devices cause some safety concerns due to a risk of electric shock and moisture-related “shorting.”
Another type of timer which has been used is a water-driven mechanical timer. One example of such a timer includes an impeller interposed between the inlet and the outlet of the valve. The impeller is rotated by the water flow. A gearing system is coupled to the impeller to activate the valve after some time period to stop the water flow. The impeller-based timer is self-running and thus does not require an independent power source. However, this type of timer suffers from inaccuracy because the rotational speed of the impeller depends entirely on the rate of water flow which may not be constant from source to source. In addition, if the water flow is of a sufficiently low pressure, the valve may not shut off.
A variety of valve assemblies have used mechanical wind-up timers. These timers typically operate using a spring which is wound up and gradually released such that the valve closes and shuts off water flow when the timer has run out. However, because such timers have a timing mechanism that does not directly couple to the valve assembly, additional torque must be generated by the spring to activate a separate mechanism to open and/or close the valve assembly, and thus the valve assembly is not as efficient. The complexity and size required of the mechanisms in many such prior art designs increase the manufacturing costs.
For certain soil and vegetation types, it is advantageous to water in intermittent increments over a pre-determined length of time. Such a watering scheme can serve to prevent short-term saturation and excess watering by limiting both the timing of a on/off watering cycle and the total length of watering time (e.g., water on for five minutes then off for ten minutes, over a three hour period). It can also help to conserve water by allowing a finite overall watering period and by allowing water from an “on cycle” to be absorbed during an intermittent “off cycle” rather than accumulating on a watering surface where it is more likely to be lost to evaporation and/or runoff. Some complex mechanical timer/valve designs and some electronic timer/valve designs have been used in an attempt to address this need. However, current wholly mechanical (i.e. non-electrical) timer valves do not presently offer an efficient design for intermittent timed watering over a set watering time, and the available electronic intermittent timers suffer from the disadvantages discussed above.
Thus, there is a need for a mechanical timer in which the mechanical components are coupled with the valve assembly to conserve space while providing increased mechanical efficiency. There is a further need for a mechanical timer which is accurate but requires no outside power source. There is also a need for a mechanical timer that includes a less complex assembly and which provides an accurate, efficient intermittent watering feature throughout a pre-determined watering cycle time.